Packing for a cooling tower

ABSTRACT

A packing for a cooling tower is assembled from elements of sheet material in which horizontally elongated flat strips and corrugated or accordion folded strips are combined. Water supplied to the top of the packing assembly flows in a film over the surfaces of the strips and drips from their edges to impinge on lower elements.

United States Patent Faigle [4 Mar. 28, 1972 [5 1 PACKING FOR A COOLING TOWER 3,235,234 2/1966 Beaudoin 261/1 l2 3,540,702 11/1970 Uyama [72] inventor: Heinz Faigle, Sagenkanal 15, 6971 Hard (voraflbergx Austria 3,281,307 10/1966 Moeller et al ..26l/112 X [22] Filed: July 6, 1970 Primary Examiner-Tim R. Miles Assistant Examiner-Steven H. Markowitz [21] Appl' 52468 Attorney-Kelman and Herman [30] Foreign Application Priority Data [57] ABSTRACT July 14, 1969 Austria ..A-6722/69 A packing f r a ling o r i assembled f l m nts f sheet material in which horizontally elongated flat strips and [52] U.S.Cl ..261/109, 261/1 12 corrug ed or cor ion fol e rip r c m in d Water [5 l Int. Cl. ..B01f 3/04 supplied to the top of the packing assembly flows in a film over [58] Field of Search ..261/ 108-1 12 the surfaces of the strips and drips from their edges to impinge s on lower elements. [56] References Cited 10 Claims, 13 Drawing Figures UNITED STATES PATENTS 1,650,140 11/1927 Kuhni ..26 l[112 PATENTEnMAm m2 SHEET 2 [IF 3 -T/Wi/VTOR wwmw/ MM F9 Glen/7s PACKING FOR A COOLING TOWER This invention relates to packings for guiding a liquid descending under the force of gravity while in contact with a gas, and particularly to a packing assembly and its use in a cooling tower.

In my earlier patent US. Pat. No. 3,485,485, I have disclosed a corrugated sheet material for use as a packing in a cooling tower. The water fed to the top end of a cooling grid made from the corrugated sheets is guided downward over the sheets in a film in which turbulence is induced by the shape of the corrugated surfaces. The coefficient of heat exchange between the descending liquid and the ambient air, which may be drawn upward by natural or artificial draft, is high.

It has now been found that even better heat transfer can be achieved if the descending liquid film is interrupted repeatedly, and the liquid dispersed in the gas in the form of drops. The drops are made to impinge on packing elements and are broken up into finer droplets by the impact. Because of the large interface of the liquid and the gas, there is not only rapid heat transfer by conduction, but also rapid evaporation of the finely dispersed liquid and cooling of the residual liquid which furnishes most of the heat of evaporation.

To achieve such a mode of operation, a packing of the invention for a cooling tower, which provides guidance for a descending liquid in contact with a gas, is made up of a plurality of guide elements of sheet material fixedly connected to each other, each element including a plurality of horizontally elongated vertically offset strip portions. A first strip portion has a plurality of angularly offset longitudinal sections so as to be accordion-pleated, corrugated, or undulating. A second strip portion defines a vertically extending surface. Respective sections of the first-mentioned strip portion constitute hollow, vertically open projections projecting from the vertically extending surface.

Other features, additionally objects, and many of the attendant advantages of this invention will be appreciated readily as the same becomes better understood by reference to the following detailed description of preferred embodiments when considered in connection with the accompanying drawings in which:

FIG. 1 shows an element of a cooling tower packing in fragmentary perspective view;

FIGS. 2 and 3 show modifications of the device of FIG. 1 in corresponding views;

FIGS. 4 to 6 illustrate additional cooling tower elements in plan view;

FIGS. 7 to 9 show the devices of FIGS. 4 to 6 in respective sections on the lines Vll-Vll, VlllVlll, and lX-IX;

FIG. 10 illustrates yet another cooling tower element of the invention in fragmentary perspective view;

FIG. 11 is a top plan view of the device of FIG. 10;

FIG. 12 shows the device of FIG. 11 in elevational section on the line Xll-Xll; and

FIG. 13 shows a tower packing assembled from elements of the type shown in FIGS. 10 to 12 in plan view.

Referring now to the drawing in detail, and initially to FIG. I, the cooling tower element seen in FIG. 1 consists of two vertically spaced, flat metal strips 1, 2 horizontally elongated in a common upright plane, and another horizontal strip 3 of the same material folded in accordion fashion and having a vertical width sufficient that respective terminal portions of each fold 4 in the strip 3 are superimposed on opposite edge portions of the strips 1, 2 and secured to the flat strips by spot welds, not seen in the drawing. The several flat sections of the strip 3 are on one side of the common vertical plane of the strips 1, 2 and are separated by transverse creases.

A multiplicity of elements identical with the one shown in FIG. 1 are normally assembled in a cooling tower in a manner partly illustrated in FIG.13 with reference to a modified embodiment of the invention. Groups of elements are superimposed in spaced relationship so that the strips 1, 2 of all ele ments of the group extend in a common vertical plane to form an apertured sheet while the accordion folded strips 3 may project from the plane in one direction or partly in one and partly in the other direction. The lower edges 5 of the lower fiat strips 1 and the lower edges 5 of the folded strips 3 are freely exposed to the ambient gas, normally air, and are toothed or scalloped to impede the flow of water along the edges, as shown in more detail in my simultaneously filed application Ser. No. 52,165 for a Heat Exchanger for Gas and Liquid.

For the convenience of manufacture, the vertical width or height h of each strip 1, 2, 3 is preferably the same so that the total height H of the element is slightly less than 311. In a typical forced draft cooling tower for water, the height H may be of the order of 10 to 15 cm., and but a very small fraction of the horizontal length of the element.

Sheets of spacedly superimposed elements are juxtaposed so as to be distributed as uniformly as possible over the cross section of the tower, and the liquid to be cooled is fed to the top edges of the sheets from perforated, horizontal distributor pipes. The water descends in a thin film over the strip 2 of each topmost element, then to the folds 4 of the folded sheet 3. Some of the liquid finds its way to the exposed, toothed edge 5' of the folded sheet, and is discharged from the edge in the form of drops which fall on a lower folded strip 3 whereby they are broken up and further descend in the tower either in the form of droplets suspended in the ambient gas, such as air rising in the tower by natural of forced draft, or by flowing in a film along lower elements. The portion of the liquid which reaches the lower fiat strip 1 of an element is similarly released from the toothed bottom edge 5 of the latter strip and impinges on the top strip 2 of a subjacent element.

The water cooled partly by thermal contact with the air and partly by loss of thermal energy due to evaporation is collected in a pan at the bottom of the tower and withdrawn for further use by means of a pump. The heated and humidified gas escapes from the open top of the tower.

The arrangement described and partly illustrated in FIG.1 makes it impossible for the descending liquid to collect in preferred flow paths or channels in which the thickness of the liquid film is relatively great. It has been found that the overall coefficient of heat transfer in cooling towers equipped with vertically spaced elements of the type illustrated in FIG.1 is significantly higher than in otherwise similar towers in which the liquid flows along ribs of corrugated sheet material even when channeling is impeded by the shape of the corrugations as shown in my afore-mentioned patent. The partial dispersion of the descending liquid in the ambient gas in the form of drops and droplets is thought to contribute materially to the observed improvement.

Modifications of the device of FIG.1 which are assembled in the same manner and function in a closely similar manner to achieve analogous results are shown in F lG.2 and 3.

The element seen in FIG.2 has a vertically central flat strip 2' and two accordion-pleated strips 3 respectively spotwelded to the two vertically offset horizontal edges of the flat strip 2. The folds in the two strips 3 are vertically aligned so that drops discharged from the lower edge of the upper strip 3 fall freely over the distance F to the upper edge of the lower folded strip 3. Even when the distance F is relatively small, contact between the liquid and the ambient gas is enhanced by the drop discharge from the upper folded strip 3'.

The element illustrated in FIG.3 is closely similar in its structure to that seen in FIG.1 and almost identical in its function. It is a unitary body of metal shaped between stamping dies on a power press. As the initially flat and relatively wide metal band passes through the press, two longitudinal rows of spacedly aligned slots are cut into the band, the slots of each row being transversely aligned with the slots of the other row, and the middle strip 3" separated by the rows of slots from the marginal strips 1", 2" is bent out of the original plane of the band to form hollow, vertically open projections analogous to the accordion folds shown in FIGS.1 and 2.

More than three strips may be vertically superimposed in a cooling tower element of the invention, and the combination of flat and folded strips may take many forms of which only three are shown in FIGSA to 9. The folding pattern also may be varied as is seen in these Figures.

The element seen in FIGSA and 7 has four superimposed strips, two fiat strips 2' being respectively at the top and bottom of the element, and two folded strips 3'" being interposed between the flat strips in such a manner that a hollow projection of one folded strip 3'" projects from the common vertical plan of the fiat strips 2'- and an adjacent hollow projection of the other folded strip projects in the opposite direction.

Spot welds, not specifically shown, connect the terminal portions of folds in each element 3' to corresponding portions of the other folded element and to adjacent edges of the flat strip, all welds being located substantially in the common plane of the flat strips.

The element illustrated in FIGS.5 and 8 differs from that described with reference to FIGSA and 7 by having vertically alternating flat strips 2" and folded strips 3", adjacent projections of the folded strips extending in opposite directions from the common plane of the flat strips so as not to interfere with the free fall of drops from the lower edges of the folded strips to corresponding strips ofthe aligned, next lower element.

As is better seen in FIGS than in FlG.4, the substantially identical folded strips 3" and 3 have recurring longitudinal portions which are located in the common vertical plane of the flat strips 2', 2", and separate two folded portions which project from the plane in opposite directions. As is evident from FlGS.7 and 8, no two projections of the element are vertically aligned.

In the element illustrated in FlGS.6 and 9, two pairs of directly superimposed folded strips 3a are separated by a fiat strip 20. The several folded strips form hollow projections which are partly aligned in a manner best seen in F169 so that some drops of the descending liquid fall from one strip to the other within the same element over a distance F which is twofifths of the total element height H, whereas other drops fall to another subjacent element, not shown.

In the additional embodiment of the invention illustrated in FlGS.l to 12, five vertically spaced, horizontal strips 11 and vertical connecting bridge portions 12 are stamped from a flat band ofwidth H in such a manner that the third or central strip is flat and defines a vertical plane from which portions of the accordion-pleated other strips project in opposite directions, the folds of the first and fifth strip being equal and deepest, and those of the second and fourth strips being shallower and also equal to each other. The several strips are connected by the bridge portions 12 in the plane of the flat central strip and arranged otherwise so that none of the hollow projections are vertically aligned, although they extend in a common transverse plane, such as the plane of FlG.l2. The drops discharged from the bottom edges of each hollow projection thus drop to the top edge of a corresponding projection on the next lower element.

In two or more horizontally juxtaposed sheets of elements, the exposed creases of the deepest folds are joined by spot welds, as is best seen in FlG.l3 to form a three-dimensional network of elements which may fill the cooling tower from wall to wall. While the arrangement offers only minimal resistance to the upward flow of air, water descending in the form of drops is unlikely to reach the bottom pan of the tower without impinging on one or several of the elements. The probability of catching such descending drops is further increased by slanting the portions of the strips which form hollow projections so as to make them oblique to the vertical plane of the central strip, as is best seen in FIG.l2. The vertically offset edges of each strip are thus also offset transversely in a horizontal direction.

Obviously, the flat and folded strips of the invention may be combined in many patterns other than those illustrated to provide a system of vertically spaced guide surfaces downwardly terminating in free edges which may be toothed, and from which the descending liquid must fall freely in the form of dro 5 until it impin es on another element.

hile spot-we] ed sheet metal structures have been described hereinabove, it will be appreciated that the elements of the invention may be made of other sheet material assembled by methods suitable for the chosen material of construction. The use of plastic sheet or plate material, of glass and other ceramic sheet material is specifically contemplated, and suitable assembly methods may employ adhesive or mechanical fasteners in an obvious manner where welding or heat sealing is not practical.

It should be understood, therefore, that the foregoing disclosure relates only to preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention set forth in the appended claims.

What is claimed is:

1. A guide arrangement for guiding a liquid descending under the force of gravity while in contact with a gas, said assembly comprising a plurality of guide elements of sheet material fixedly connected to each other, each element including a plurality of horizontally elongated, vertically offset strip portions, a first one of said strip portions having a plurality of angularly offset longitudinal sections, a second strip portion defining a vertically extending surface, respective sections of said first strip portion constituting hollow, vertically open projections projecting from said vertically extending surface.

2. An arrangement as set forth in claim 1, wherein said second strip portion is substantially flat and extends in said vertically extending surface, said surface being a plane.

3, An assembly as set forth in claim 2, wherein said sections of said first strip portion are separated by transverse creases and are substantially flat.

4. An arrangement as set forth in claim 2, wherein said projections project from said vertically extending plane in a common direction.

5. An arrangement as set forth in claim 1, wherein a third one of said strip portions has a plurality of longitudinal sections constituting hollow projections projecting from said vertically extending surface.

6. An arrangement as set forth in claim 5, wherein the projections of said first and third sections are vertically spaced, said second strip portion being interposed between said first and third strip portions and fixedly connecting the same.

7. An arrangement as set forth in claim 6, wherein the dimensions of said projections of said first and third strip portions in a direction away from said surface are different.

8. An arrangement as set forth in claim 1, wherein said elements are vertically spaced from each other, said first strip portions having each two vertically offset, exposed, longitudinal edges.

9. An arrangement as set forth in claim 1, wherein said guide elements are vertically spacedly superposed in fixed relationship, the arrangement further comprising supply means for feeding said liquid to the topmost guide element and for withdrawing liquid from the lowermost element.

10. An arrangement as set forth in claim 8, wherein the lower ones of said edges are toothed. 

1. A guide arrangement for guiding a liquid descending under the force of gravity while in contact with a gas, said assembly comprising a plurality of guide elements of sheet material fixedly connected to each other, each element including a plurality of horizontally elongated, vertically offset strip portions, a first one of said strip portions having a plurality of angularly offset longitudinal sections, a second strip portion defining a vertically extending surface, respective sections of said first strip portion constituting hollow, vertically open projections projecting from said vertically extending surface.
 2. An arrangement as set forth in claim 1, wherein said second strip portion is substantially flat and extends in said vertically extending surface, said surface being a plane.
 3. An assembly as set forth in claim 2, wherein said sections of said first strip portion are separated by transverse creases and are substantially flat.
 4. An arrangement as set forth in claim 2, wherein said projections project from said vertically extending plane in a common direction.
 5. An arrangement as set forth in claim 1, wherein a third one of said strip portions has a plurality of longitudinal sections constituting hollow projections projecting from said vertically extending surface.
 6. An arrangement as set forth in claim 5, wherein the projections of said first and third sections are vertically spaced, said second strip portion being interposed between said first and third strip portions and fixedly connecting the same.
 7. An arrangement as set forth in claim 6, wherein the dimensions of said projections of said first and third strip portions in a direction away from said surface are different.
 8. An arrangement as set forth in claim 1, wherein said elements are vertically spaced from each other, said first strip portions having each two vertically offset, exposed, longitudinal edges.
 9. An arrangement as set forth in claim 1, wherein said guide elements are vertically spacedly superposed in fixed relationship, the arrangement further comprising supply means for feeding said liquid to the topmost guide element and for withdrawing liquid from the lowermost element.
 10. An arrangement as set forth in claim 8, wherein the lower ones of said edges are toothed. 